Earnings (Loss) Per Share of Common Stock - Reconciliation of Numerator and Denominator for Basic and Diluted Earnings (loss) Per Share Calculation (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Earnings Per Share [Abstract]
Net income (loss) available to common stockholders		$ 16.8	$ 10.8	$ (24.1)	$ (1.3)
Weighted average number of common shares outstanding - basic		93,504,000	93,207,000	93,409,000	102,705,000
Basic earnings (loss) per share		$ 0.18	$ 0.12	$ (0.26)	$ (0.01)
Weighted average number of common shares outstanding – diluted		94,001,000	93,436,000	93,409,000	102,705,000
Diluted earnings (loss) per share		$ 0.18	$ 0.12	$ (0.26)	$ (0.01)
Weighted average number of anti-dilutive options and restricted stock	[1]	4,663,000	4,180,000	4,712,000	4,968,000

[1] Weighted average number of anti-dilutive options is based upon the average closing price of the Company’s common stock on the NYSE for the period